/*
 * Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

/*
 * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.text;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import sun.misc.FloatingDecimal;

/**
 * Digit List. Private to DecimalFormat.
 * Handles the transcoding
 * between numeric values and strings of characters.  Only handles
 * non-negative numbers.  The division of labor between DigitList and
 * DecimalFormat is that DigitList handles the radix 10 representation
 * issues; DecimalFormat handles the locale-specific issues such as
 * positive/negative, grouping, decimal point, currency, and so on.
 *
 * A DigitList is really a representation of a floating point value.
 * It may be an integer value; we assume that a double has sufficient
 * precision to represent all digits of a long.
 *
 * The DigitList representation consists of a string of characters,
 * which are the digits radix 10, from '0' to '9'.  It also has a radix
 * 10 exponent associated with it.  The value represented by a DigitList
 * object can be computed by mulitplying the fraction f, where 0 <= f < 1,
 * derived by placing all the digits of the list to the right of the
 * decimal point, by 10^exponent.
 *
 * @author Mark Davis, Alan Liu
 * @see Locale
 * @see Format
 * @see NumberFormat
 * @see DecimalFormat
 * @see ChoiceFormat
 * @see MessageFormat
 */
final class DigitList implements Cloneable {

  /**
   * The maximum number of significant digits in an IEEE 754 double, that
   * is, in a Java double.  This must not be increased, or garbage digits
   * will be generated, and should not be decreased, or accuracy will be lost.
   */
  public static final int MAX_COUNT = 19; // == Long.toString(Long.MAX_VALUE).length()

  /**
   * These data members are intentionally public and can be set directly.
   *
   * The value represented is given by placing the decimal point before
   * digits[decimalAt].  If decimalAt is < 0, then leading zeros between
   * the decimal point and the first nonzero digit are implied.  If decimalAt
   * is > count, then trailing zeros between the digits[count-1] and the
   * decimal point are implied.
   *
   * Equivalently, the represented value is given by f * 10^decimalAt.  Here
   * f is a value 0.1 <= f < 1 arrived at by placing the digits in Digits to
   * the right of the decimal.
   *
   * DigitList is normalized, so if it is non-zero, figits[0] is non-zero.  We
   * don't allow denormalized numbers because our exponent is effectively of
   * unlimited magnitude.  The count value contains the number of significant
   * digits present in digits[].
   *
   * Zero is represented by any DigitList with count == 0 or with each digits[i]
   * for all i <= count == '0'.
   */
  public int decimalAt = 0;
  public int count = 0;
  public char[] digits = new char[MAX_COUNT];

  private char[] data;
  private RoundingMode roundingMode = RoundingMode.HALF_EVEN;
  private boolean isNegative = false;

  /**
   * Return true if the represented number is zero.
   */
  boolean isZero() {
    for (int i = 0; i < count; ++i) {
      if (digits[i] != '0') {
        return false;
      }
    }
    return true;
  }

  /**
   * Set the rounding mode
   */
  void setRoundingMode(RoundingMode r) {
    roundingMode = r;
  }

  /**
   * Clears out the digits.
   * Use before appending them.
   * Typically, you set a series of digits with append, then at the point
   * you hit the decimal point, you set myDigitList.decimalAt = myDigitList.count;
   * then go on appending digits.
   */
  public void clear() {
    decimalAt = 0;
    count = 0;
  }

  /**
   * Appends a digit to the list, extending the list when necessary.
   */
  public void append(char digit) {
    if (count == digits.length) {
      char[] data = new char[count + 100];
      System.arraycopy(digits, 0, data, 0, count);
      digits = data;
    }
    digits[count++] = digit;
  }

  /**
   * Utility routine to get the value of the digit list
   * If (count == 0) this throws a NumberFormatException, which
   * mimics Long.parseLong().
   */
  public final double getDouble() {
    if (count == 0) {
      return 0.0;
    }

    StringBuffer temp = getStringBuffer();
    temp.append('.');
    temp.append(digits, 0, count);
    temp.append('E');
    temp.append(decimalAt);
    return Double.parseDouble(temp.toString());
  }

  /**
   * Utility routine to get the value of the digit list.
   * If (count == 0) this returns 0, unlike Long.parseLong().
   */
  public final long getLong() {
    // for now, simple implementation; later, do proper IEEE native stuff

    if (count == 0) {
      return 0;
    }

    // We have to check for this, because this is the one NEGATIVE value
    // we represent.  If we tried to just pass the digits off to parseLong,
    // we'd get a parse failure.
    if (isLongMIN_VALUE()) {
      return Long.MIN_VALUE;
    }

    StringBuffer temp = getStringBuffer();
    temp.append(digits, 0, count);
    for (int i = count; i < decimalAt; ++i) {
      temp.append('0');
    }
    return Long.parseLong(temp.toString());
  }

  public final BigDecimal getBigDecimal() {
    if (count == 0) {
      if (decimalAt == 0) {
        return BigDecimal.ZERO;
      } else {
        return new BigDecimal("0E" + decimalAt);
      }
    }

    if (decimalAt == count) {
      return new BigDecimal(digits, 0, count);
    } else {
      return new BigDecimal(digits, 0, count).scaleByPowerOfTen(decimalAt - count);
    }
  }

  /**
   * Return true if the number represented by this object can fit into
   * a long.
   *
   * @param isPositive true if this number should be regarded as positive
   * @param ignoreNegativeZero true if -0 should be regarded as identical to +0; otherwise they are
   * considered distinct
   * @return true if this number fits into a Java long
   */
  boolean fitsIntoLong(boolean isPositive, boolean ignoreNegativeZero) {
    // Figure out if the result will fit in a long.  We have to
    // first look for nonzero digits after the decimal point;
    // then check the size.  If the digit count is 18 or less, then
    // the value can definitely be represented as a long.  If it is 19
    // then it may be too large.

    // Trim trailing zeros.  This does not change the represented value.
    while (count > 0 && digits[count - 1] == '0') {
      --count;
    }

    if (count == 0) {
      // Positive zero fits into a long, but negative zero can only
      // be represented as a double. - bug 4162852
      return isPositive || ignoreNegativeZero;
    }

    if (decimalAt < count || decimalAt > MAX_COUNT) {
      return false;
    }

    if (decimalAt < MAX_COUNT) {
      return true;
    }

    // At this point we have decimalAt == count, and count == MAX_COUNT.
    // The number will overflow if it is larger than 9223372036854775807
    // or smaller than -9223372036854775808.
    for (int i = 0; i < count; ++i) {
      char dig = digits[i], max = LONG_MIN_REP[i];
      if (dig > max) {
        return false;
      }
      if (dig < max) {
        return true;
      }
    }

    // At this point the first count digits match.  If decimalAt is less
    // than count, then the remaining digits are zero, and we return true.
    if (count < decimalAt) {
      return true;
    }

    // Now we have a representation of Long.MIN_VALUE, without the leading
    // negative sign.  If this represents a positive value, then it does
    // not fit; otherwise it fits.
    return !isPositive;
  }

  /**
   * Set the digit list to a representation of the given double value.
   * This method supports fixed-point notation.
   *
   * @param isNegative Boolean value indicating whether the number is negative.
   * @param source Value to be converted; must not be Inf, -Inf, Nan, or a value <= 0.
   * @param maximumFractionDigits The most fractional digits which should be converted.
   */
  final void set(boolean isNegative, double source, int maximumFractionDigits) {
    set(isNegative, source, maximumFractionDigits, true);
  }

  /**
   * Set the digit list to a representation of the given double value.
   * This method supports both fixed-point and exponential notation.
   *
   * @param isNegative Boolean value indicating whether the number is negative.
   * @param source Value to be converted; must not be Inf, -Inf, Nan, or a value <= 0.
   * @param maximumDigits The most fractional or total digits which should be converted.
   * @param fixedPoint If true, then maximumDigits is the maximum fractional digits to be converted.
   * If false, total digits.
   */
  final void set(boolean isNegative, double source, int maximumDigits, boolean fixedPoint) {

    FloatingDecimal.BinaryToASCIIConverter fdConverter = FloatingDecimal
        .getBinaryToASCIIConverter(source);
    boolean hasBeenRoundedUp = fdConverter.digitsRoundedUp();
    boolean valueExactAsDecimal = fdConverter.decimalDigitsExact();
    assert !fdConverter.isExceptional();
    String digitsString = fdConverter.toJavaFormatString();

    set(isNegative, digitsString,
        hasBeenRoundedUp, valueExactAsDecimal,
        maximumDigits, fixedPoint);
  }

  /**
   * Generate a representation of the form DDDDD, DDDDD.DDDDD, or
   * DDDDDE+/-DDDDD.
   *
   * @param roundedUp whether or not rounding up has already happened.
   * @param valueExactAsDecimal whether or not collected digits provide an exact decimal
   * representation of the value.
   */
  private void set(boolean isNegative, String s,
      boolean roundedUp, boolean valueExactAsDecimal,
      int maximumDigits, boolean fixedPoint) {

    this.isNegative = isNegative;
    int len = s.length();
    char[] source = getDataChars(len);
    s.getChars(0, len, source, 0);

    decimalAt = -1;
    count = 0;
    int exponent = 0;
    // Number of zeros between decimal point and first non-zero digit after
    // decimal point, for numbers < 1.
    int leadingZerosAfterDecimal = 0;
    boolean nonZeroDigitSeen = false;

    for (int i = 0; i < len; ) {
      char c = source[i++];
      if (c == '.') {
        decimalAt = count;
      } else if (c == 'e' || c == 'E') {
        exponent = parseInt(source, i, len);
        break;
      } else {
        if (!nonZeroDigitSeen) {
          nonZeroDigitSeen = (c != '0');
          if (!nonZeroDigitSeen && decimalAt != -1) {
            ++leadingZerosAfterDecimal;
          }
        }
        if (nonZeroDigitSeen) {
          digits[count++] = c;
        }
      }
    }
    if (decimalAt == -1) {
      decimalAt = count;
    }
    if (nonZeroDigitSeen) {
      decimalAt += exponent - leadingZerosAfterDecimal;
    }

    if (fixedPoint) {
      // The negative of the exponent represents the number of leading
      // zeros between the decimal and the first non-zero digit, for
      // a value < 0.1 (e.g., for 0.00123, -decimalAt == 2).  If this
      // is more than the maximum fraction digits, then we have an underflow
      // for the printed representation.
      if (-decimalAt > maximumDigits) {
        // Handle an underflow to zero when we round something like
        // 0.0009 to 2 fractional digits.
        count = 0;
        return;
      } else if (-decimalAt == maximumDigits) {
        // If we round 0.0009 to 3 fractional digits, then we have to
        // create a new one digit in the least significant location.
        if (shouldRoundUp(0, roundedUp, valueExactAsDecimal)) {
          count = 1;
          ++decimalAt;
          digits[0] = '1';
        } else {
          count = 0;
        }
        return;
      }
      // else fall through
    }

    // Eliminate trailing zeros.
    while (count > 1 && digits[count - 1] == '0') {
      --count;
    }

    // Eliminate digits beyond maximum digits to be displayed.
    // Round up if appropriate.
    round(fixedPoint ? (maximumDigits + decimalAt) : maximumDigits,
        roundedUp, valueExactAsDecimal);

  }

  /**
   * Round the representation to the given number of digits.
   *
   * @param maximumDigits The maximum number of digits to be shown.
   * @param alreadyRounded whether or not rounding up has already happened.
   * @param valueExactAsDecimal whether or not collected digits provide an exact decimal
   * representation of the value.
   *
   * Upon return, count will be less than or equal to maximumDigits.
   */
  private final void round(int maximumDigits,
      boolean alreadyRounded,
      boolean valueExactAsDecimal) {
    // Eliminate digits beyond maximum digits to be displayed.
    // Round up if appropriate.
    if (maximumDigits >= 0 && maximumDigits < count) {
      if (shouldRoundUp(maximumDigits, alreadyRounded, valueExactAsDecimal)) {
        // Rounding up involved incrementing digits from LSD to MSD.
        // In most cases this is simple, but in a worst case situation
        // (9999..99) we have to adjust the decimalAt value.
        for (; ; ) {
          --maximumDigits;
          if (maximumDigits < 0) {
            // We have all 9's, so we increment to a single digit
            // of one and adjust the exponent.
            digits[0] = '1';
            ++decimalAt;
            maximumDigits = 0; // Adjust the count
            break;
          }

          ++digits[maximumDigits];
          if (digits[maximumDigits] <= '9') {
            break;
          }
          // digits[maximumDigits] = '0'; // Unnecessary since we'll truncate this
        }
        ++maximumDigits; // Increment for use as count
      }
      count = maximumDigits;

      // Eliminate trailing zeros.
      while (count > 1 && digits[count - 1] == '0') {
        --count;
      }
    }
  }


  /**
   * Return true if truncating the representation to the given number
   * of digits will result in an increment to the last digit.  This
   * method implements the rounding modes defined in the
   * java.math.RoundingMode class.
   * [bnf]
   *
   * @param maximumDigits the number of digits to keep, from 0 to <code>count-1</code>.  If 0, then
   * all digits are rounded away, and this method returns true if a one should be generated (e.g.,
   * formatting 0.09 with "#.#").
   * @param alreadyRounded whether or not rounding up has already happened.
   * @param valueExactAsDecimal whether or not collected digits provide an exact decimal
   * representation of the value.
   * @return true if digit <code>maximumDigits-1</code> should be incremented
   * @throws ArithmeticException if rounding is needed with rounding mode being set to
   * RoundingMode.UNNECESSARY
   */
  private boolean shouldRoundUp(int maximumDigits,
      boolean alreadyRounded,
      boolean valueExactAsDecimal) {
    if (maximumDigits < count) {
            /*
             * To avoid erroneous double-rounding or truncation when converting
             * a binary double value to text, information about the exactness
             * of the conversion result in FloatingDecimal, as well as any
             * rounding done, is needed in this class.
             *
             * - For the  HALF_DOWN, HALF_EVEN, HALF_UP rounding rules below:
             *   In the case of formating float or double, We must take into
             *   account what FloatingDecimal has done in the binary to decimal
             *   conversion.
             *
             *   Considering the tie cases, FloatingDecimal may round up the
             *   value (returning decimal digits equal to tie when it is below),
             *   or "truncate" the value to the tie while value is above it,
             *   or provide the exact decimal digits when the binary value can be
             *   converted exactly to its decimal representation given formating
             *   rules of FloatingDecimal ( we have thus an exact decimal
             *   representation of the binary value).
             *
             *   - If the double binary value was converted exactly as a decimal
             *     value, then DigitList code must apply the expected rounding
             *     rule.
             *
             *   - If FloatingDecimal already rounded up the decimal value,
             *     DigitList should neither round up the value again in any of
             *     the three rounding modes above.
             *
             *   - If FloatingDecimal has truncated the decimal value to
             *     an ending '5' digit, DigitList should round up the value in
             *     all of the three rounding modes above.
             *
             *
             *   This has to be considered only if digit at maximumDigits index
             *   is exactly the last one in the set of digits, otherwise there are
             *   remaining digits after that position and we don't have to consider
             *   what FloatingDecimal did.
             *
             * - Other rounding modes are not impacted by these tie cases.
             *
             * - For other numbers that are always converted to exact digits
             *   (like BigInteger, Long, ...), the passed alreadyRounded boolean
             *   have to be  set to false, and valueExactAsDecimal has to be set to
             *   true in the upper DigitList call stack, providing the right state
             *   for those situations..
             */

      switch (roundingMode) {
        case UP:
          for (int i = maximumDigits; i < count; ++i) {
            if (digits[i] != '0') {
              return true;
            }
          }
          break;
        case DOWN:
          break;
        case CEILING:
          for (int i = maximumDigits; i < count; ++i) {
            if (digits[i] != '0') {
              return !isNegative;
            }
          }
          break;
        case FLOOR:
          for (int i = maximumDigits; i < count; ++i) {
            if (digits[i] != '0') {
              return isNegative;
            }
          }
          break;
        case HALF_UP:
        case HALF_DOWN:
          if (digits[maximumDigits] > '5') {
            // Value is above tie ==> must round up
            return true;
          } else if (digits[maximumDigits] == '5') {
            // Digit at rounding position is a '5'. Tie cases.
            if (maximumDigits != (count - 1)) {
              // There are remaining digits. Above tie => must round up
              return true;
            } else {
              // Digit at rounding position is the last one !
              if (valueExactAsDecimal) {
                // Exact binary representation. On the tie.
                // Apply rounding given by roundingMode.
                return roundingMode == RoundingMode.HALF_UP;
              } else {
                // Not an exact binary representation.
                // Digit sequence either rounded up or truncated.
                // Round up only if it was truncated.
                return !alreadyRounded;
              }
            }
          }
          // Digit at rounding position is < '5' ==> no round up.
          // Just let do the default, which is no round up (thus break).
          break;
        case HALF_EVEN:
          // Implement IEEE half-even rounding
          if (digits[maximumDigits] > '5') {
            return true;
          } else if (digits[maximumDigits] == '5') {
            if (maximumDigits == (count - 1)) {
              // the rounding position is exactly the last index :
              if (alreadyRounded)
              // If FloatingDecimal rounded up (value was below tie),
              // then we should not round up again.
              {
                return false;
              }

              if (!valueExactAsDecimal)
              // Otherwise if the digits don't represent exact value,
              // value was above tie and FloatingDecimal truncated
              // digits to tie. We must round up.
              {
                return true;
              } else {
                // This is an exact tie value, and FloatingDecimal
                // provided all of the exact digits. We thus apply
                // HALF_EVEN rounding rule.
                return ((maximumDigits > 0) &&
                    (digits[maximumDigits - 1] % 2 != 0));
              }
            } else {
              // Rounds up if it gives a non null digit after '5'
              for (int i = maximumDigits + 1; i < count; ++i) {
                if (digits[i] != '0') {
                  return true;
                }
              }
            }
          }
          break;
        case UNNECESSARY:
          for (int i = maximumDigits; i < count; ++i) {
            if (digits[i] != '0') {
              throw new ArithmeticException(
                  "Rounding needed with the rounding mode being set to RoundingMode.UNNECESSARY");
            }
          }
          break;
        default:
          assert false;
      }
    }
    return false;
  }

  /**
   * Utility routine to set the value of the digit list from a long
   */
  final void set(boolean isNegative, long source) {
    set(isNegative, source, 0);
  }

  /**
   * Set the digit list to a representation of the given long value.
   *
   * @param isNegative Boolean value indicating whether the number is negative.
   * @param source Value to be converted; must be >= 0 or == Long.MIN_VALUE.
   * @param maximumDigits The most digits which should be converted. If maximumDigits is lower than
   * the number of significant digits in source, the representation will be rounded.  Ignored if <=
   * 0.
   */
  final void set(boolean isNegative, long source, int maximumDigits) {
    this.isNegative = isNegative;

    // This method does not expect a negative number. However,
    // "source" can be a Long.MIN_VALUE (-9223372036854775808),
    // if the number being formatted is a Long.MIN_VALUE.  In that
    // case, it will be formatted as -Long.MIN_VALUE, a number
    // which is outside the legal range of a long, but which can
    // be represented by DigitList.
    if (source <= 0) {
      if (source == Long.MIN_VALUE) {
        decimalAt = count = MAX_COUNT;
        System.arraycopy(LONG_MIN_REP, 0, digits, 0, count);
      } else {
        decimalAt = count = 0; // Values <= 0 format as zero
      }
    } else {
      // Rewritten to improve performance.  I used to call
      // Long.toString(), which was about 4x slower than this code.
      int left = MAX_COUNT;
      int right;
      while (source > 0) {
        digits[--left] = (char) ('0' + (source % 10));
        source /= 10;
      }
      decimalAt = MAX_COUNT - left;
      // Don't copy trailing zeros.  We are guaranteed that there is at
      // least one non-zero digit, so we don't have to check lower bounds.
      for (right = MAX_COUNT - 1; digits[right] == '0'; --right) {
        ;
      }
      count = right - left + 1;
      System.arraycopy(digits, left, digits, 0, count);
    }
    if (maximumDigits > 0) {
      round(maximumDigits, false, true);
    }
  }

  /**
   * Set the digit list to a representation of the given BigDecimal value.
   * This method supports both fixed-point and exponential notation.
   *
   * @param isNegative Boolean value indicating whether the number is negative.
   * @param source Value to be converted; must not be a value <= 0.
   * @param maximumDigits The most fractional or total digits which should be converted.
   * @param fixedPoint If true, then maximumDigits is the maximum fractional digits to be converted.
   * If false, total digits.
   */
  final void set(boolean isNegative, BigDecimal source, int maximumDigits, boolean fixedPoint) {
    String s = source.toString();
    extendDigits(s.length());

    set(isNegative, s,
        false, true,
        maximumDigits, fixedPoint);
  }

  /**
   * Set the digit list to a representation of the given BigInteger value.
   *
   * @param isNegative Boolean value indicating whether the number is negative.
   * @param source Value to be converted; must be >= 0.
   * @param maximumDigits The most digits which should be converted. If maximumDigits is lower than
   * the number of significant digits in source, the representation will be rounded.  Ignored if <=
   * 0.
   */
  final void set(boolean isNegative, BigInteger source, int maximumDigits) {
    this.isNegative = isNegative;
    String s = source.toString();
    int len = s.length();
    extendDigits(len);
    s.getChars(0, len, digits, 0);

    decimalAt = len;
    int right;
    for (right = len - 1; right >= 0 && digits[right] == '0'; --right) {
      ;
    }
    count = right + 1;

    if (maximumDigits > 0) {
      round(maximumDigits, false, true);
    }
  }

  /**
   * equality test between two digit lists.
   */
  public boolean equals(Object obj) {
    if (this == obj)                      // quick check
    {
      return true;
    }
    if (!(obj instanceof DigitList))         // (1) same object?
    {
      return false;
    }
    DigitList other = (DigitList) obj;
    if (count != other.count ||
        decimalAt != other.decimalAt) {
      return false;
    }
    for (int i = 0; i < count; i++) {
      if (digits[i] != other.digits[i]) {
        return false;
      }
    }
    return true;
  }

  /**
   * Generates the hash code for the digit list.
   */
  public int hashCode() {
    int hashcode = decimalAt;

    for (int i = 0; i < count; i++) {
      hashcode = hashcode * 37 + digits[i];
    }

    return hashcode;
  }

  /**
   * Creates a copy of this object.
   *
   * @return a clone of this instance.
   */
  public Object clone() {
    try {
      DigitList other = (DigitList) super.clone();
      char[] newDigits = new char[digits.length];
      System.arraycopy(digits, 0, newDigits, 0, digits.length);
      other.digits = newDigits;
      other.tempBuffer = null;
      return other;
    } catch (CloneNotSupportedException e) {
      throw new InternalError(e);
    }
  }

  /**
   * Returns true if this DigitList represents Long.MIN_VALUE;
   * false, otherwise.  This is required so that getLong() works.
   */
  private boolean isLongMIN_VALUE() {
    if (decimalAt != count || count != MAX_COUNT) {
      return false;
    }

    for (int i = 0; i < count; ++i) {
      if (digits[i] != LONG_MIN_REP[i]) {
        return false;
      }
    }

    return true;
  }

  private static final int parseInt(char[] str, int offset, int strLen) {
    char c;
    boolean positive = true;
    if ((c = str[offset]) == '-') {
      positive = false;
      offset++;
    } else if (c == '+') {
      offset++;
    }

    int value = 0;
    while (offset < strLen) {
      c = str[offset++];
      if (c >= '0' && c <= '9') {
        value = value * 10 + (c - '0');
      } else {
        break;
      }
    }
    return positive ? value : -value;
  }

  // The digit part of -9223372036854775808L
  private static final char[] LONG_MIN_REP = "9223372036854775808".toCharArray();

  public String toString() {
    if (isZero()) {
      return "0";
    }
    StringBuffer buf = getStringBuffer();
    buf.append("0.");
    buf.append(digits, 0, count);
    buf.append("x10^");
    buf.append(decimalAt);
    return buf.toString();
  }

  private StringBuffer tempBuffer;

  private StringBuffer getStringBuffer() {
    if (tempBuffer == null) {
      tempBuffer = new StringBuffer(MAX_COUNT);
    } else {
      tempBuffer.setLength(0);
    }
    return tempBuffer;
  }

  private void extendDigits(int len) {
    if (len > digits.length) {
      digits = new char[len];
    }
  }

  private final char[] getDataChars(int length) {
    if (data == null || data.length < length) {
      data = new char[length];
    }
    return data;
  }
}
